Weight standardization machine

ABSTRACT

A weight standardization machine for workpieces such as connecting rods for internal combustion engines and the like, said machine having a load station from which workpieces are successively advanced to a weight station whereat a weighing scale determines the magnitude of overweight of successive workpieces thereon, and to a work station whereat successive workpieces are clamped for removal of excess weight as by a milling machine, the overweight information determined by the weighing scale being converted and stored to control the feed stroke of the milling cutter to remove precisely the right amount of metal when the previously weighed workpieces are successively clamped at the work station, and there being provided a sensing means responsive to engagement of the milling cutter with the workpiece to initiate said predetermined feed stroke as determined by the weighing scale converter.

United States Patent Forster et a1.

[ Nov. 13, 1973 1 1 WEIGHT STANDARDIZATION MACHTNE [75] Inventors: PeterE. Forster, Brecksville; Ronald R. Nowak, Kirtland, both of Ohio [73]Assignee: The Motch & Merryweather Machinery Co., Cleveland, Ohio [22]Filed: June 8, 1972 [21] Appl. No.: 260,814

[52] US. Cl 177/60, 177/67, 177/82, 83/77 [51] Int. Cl G01g 13/00 [58]Field of Search 177/60, 62-64, 177/66, 67, 82, 89, 105; 83/77 [56]References Cited UNlTED STATES PATENTS 970,826 9/1910 Hoyt 177/60 X1,041,278 10/1912 l-layssen et al.. 177/60 X 2,753,144 7/1956 Seem177/60 X- 2,812,792 1111957 Allbright l77/60 X 2,903,032 9/1959 Cervene177/60 X 3,175,438 3/1965 'Johnson... 83/77 X 3,274,377 9/1966 Morison.177/60 X 3,476,198 11/1969 Francis 177/60 X Primary Examiner-Richard B.Wilkinson Assistant Examiner-Stanley .1. Witkowski Att0mey-Walter Maky[5 7] ABSTRACT A weight standardization machine for workpieces such asconnecting rods for internal combustion engines and the like, saidmachine having a load station from which workpieces are successivelyadvanced to a weight station whereat a weighing scale determines themagnitude of overweight of successive workpieces thereon, and to a workstation whereat successive workpieces are clamped for removal of excessweight as by a milling machine, the overweight information determined bythe weighing scale being converted and stored to control the feed strokeof the milling cutter to remove precisely the right amount of metal whenthe previously weighed workpieces are successively clamped at the workstation, and there being provided a sensing means responsive toengagement of the milling cutter with the workpiece to initiate saidpredeter- 7 Claims, 9 Drawing Figures l nai ed i Y CKWIEIGH UNLOAD iSHEET u [If 5 PATENTED am 13 I973 PATENIEnuuv 13 I975 3.771. 61 3 SHEET50F 5 4 T 4POWER SUPPLY 1| LT 67 W MEASU ES WE'GHT SENSES"RATE OFCHANGE" REMOVAL 69 ,VCONVERTER W STWAL STOCK REMOVAL IN THOUSANDS OF ANINCH V 10 5M MEMORY UNTIL PART 72 REACHES MILLING STATION w v COUNTERCOUNT DOWN 59 57 T REVERSE MOTO M 60 58 5| s5 PULSE GENERATOR TQ I l'mu'" m 5.29. 5 i I j 62 64 ea MONITOR CURRENT OLAMP 6 82 cLAMP 86 IWEIGHT STANDARDIZATION MACHINE BACKGROUND OF THE INVENTION In the weightstandardization of workpieces such as connecting rods one known practiceis to pre-rnill the weight bosses at the crank pin and wrist pin ends ofthe connecting rod to provide a reference plane at each end which is aspecified accurate distance from the axis of the respective crank pinand wrist pin bores. After such pre-milling operation, the connectingrod is weighed and the scale determines how much metal is to be removedfrom the respective weight bosses thus to set the advance of the cuttingtools from such premilled reference planes.

Another known method of standardizing the weight of workpieces such asconnecting rods is to weigh the connecting rod to determine themagnitude of overweight of the crank pin and wrist pin ends thereof andthen by means of a probe on the machine tool determine the locations ofthe end faces of the weight bosses whereupon the cutting tools areadvanced predetermined distances from such probed locations.

SUMMARY OF THE INVENTION With the foregoing in mind, it is a primaryobject of this invention to provide a weight standardization machineapplicable to connecting rods, for example, which eliminates theaforesaid pre-milling operation and which eliminates the necessity ofproviding a probe on the machine to determine the location of the endfaces of the weight bosses of the connecting rods.

vIt is another object of this invention to provide a weightstandardization machine which is of substantially reduced cost by virtueof the elimination of the pre-milling station and which increases theproductivity of themachine as compared with known machines byeliminating the probing operation and further by providing idle stationsbetween the load, weigh, and work stations so that the workpieces may bequickly indexed from the respective idle stations to the weigh and workstations.

Other objects and advantages of the present invention will becomeapparent as the following description proceeds.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a top plan view indiagrammatic form of a preferred form of a machine for standardizing theweight of workpieces such as connecting rods;

FIG. 2 is a front elevation view on somewhat enlarged scale as viewedalong the line 2-2, FIG. 1;

FIGS. 3, 4 and are top plan, and end elevation views as viewed along therespective lines 3-3, 4-4 and 5-5 of FIG. 2;

FIG. 6 is a fragmentary front elevation view at the weigh station onstill further enlarged scale;

FIG. '7 is a cross section view taken substantially along the line 7-7,FIG. 6; I v

FIG. 8 is a cross section view of the milling machine takensubstantially along the line 8-8, FIG. 3, and illustrating in additionthe control for achieving automatic removal of a prescribed amount ofmetal from the weight bosses as determined by the weighing scale; and

FIG. 9 is a cross section view similar to FIG. 8 except illustrating amodified form of milling machine.

DETAILED DESCRIPTION OF THE DRAWING Referring first to FIG. 1, theweight standardization machine M herein is employed for standardizingthe weight of workpieces such as internal combustion engine connectingrods C as by milling excess weight from weight bosses at the crank pinand wrist pin ends thereof. By way of illustration, the weightstandardization machine M in FIG. I comprises 10 stations as follows:

Load station Idle Station Weighing Station Idle Station Milling StationIdle Station Idle Station Check Weighing Station 8 Reject Station 9Unload Station l0 Referring now to FIGS. I through 8 the weightstandardization machine M comprises a base ll having parallellongitudinal rails 12 for supporting the connecting rods C in horizontalposition with their crank pin and wrist pin ends resting upon the rails12 and with the axes of the crank pin and wrist pin bores disposed invertical position. As aforesaid, the first station is the loadingstation 1 and at that station connecting rods C may be sequentiallymanually loaded onto the rails 12 or, if desired, automated conveyormeans may be provided to successively transfer connecting rods C to saidloading station 1, from which they are successively indexed through thestations 2 through 10 by means now to be described.

The base 11 has upstanding columns 14 on which the upper frame members15 are supported, said frame members 15 having secured thereon pairs ofbrackets 16 in which bell cranks 17, 18 and 19 are pivotally supportedfor actuation by the actuator bar 20 which is longitudinallyreciprocably supported by the bearings 21, reciprocation of said barbeing effected by the cylinder 23 which has its piston rod 24 connectedto said bar 26. Said bar has thereon several collars 25 which havevertical slots to engage the upper ends of the bell cranks I7, 18 and 19and the other ends of the bell cranks I7, 18 and 19 are engaged withvertically guided rods 26 having pilots 27 to enter the bores of theconnecting rods C, with vertically guided rods 28 having T-slotconnections 29 with the index bar 30, and with vertically guided rods 31to raise and lower the sections 32 of the rails 12 at the weigh andcheck weigh stations 3 and 8. The index bar 30 is reciprocatedlongitudinally along the T-slot connections 29 as by means of thecylinder 34.

The index bar 30 has connecting rod engaging members 35 secured theretowhich are adapted to engage the rod portions ofthe respective connectingrods C at the load, weigh, milling, check weigh, and reject stations 1,3, 5, 8 and 9 to advance the connecting rods C to the respectivesucceeding stations when the lowered index bar 30 is moved to the rightfrom the FIG. 2 position. The index bar 30 also has connecting rodengaging members 36 in the form of parallel pins with beveled ends toenter the connecting rod bores for precision indexing from the idlestation 2 to the weigh station 3, from the idle station 4 to the millingor work station 5, from the idle station 6 to the idle station 7, andfrom the idle station 7 to the check weigh station 8 when the loweredindex bar 30 is moved to the right from the FIG. 2 position.

When the bell crank actuating bar 20 is moved to the left position asshown in FIG. 2, the pilots 27 are moved downwardly by the bell cranks17 to retain the connecting rods C in indexed position and the index bar30 together with the connecting rod engaging members 35 and 36 arelifted out of engagement with the respective connecting rods C wherebythe cylinder 34 may be actuated to shift the index bar 30 to the leftposition as shown in FIG. 2 to position the respective engaging members35 and 36 above the connecting rods C at the respective stations. Whenthe pilot 27 at the idle station 4 is lowered, it trips a switch 37 toenergize the hydraulic clamp cylinder 38 at the milling station to causethe piloted clamp members 39 to firmly clamp the connecting rod Cagainst the rails 12 which arebacked up w by a block 40 on the base 11.

When the index bar 30 is in lowered position and when it is advanced,the rail sections 32 are even with the preceding and following portionsof the rails 12 whereby the connecting rods at stations 1 to 9 areadvanced to the succeeding stations 2 to It). Now, when the index bar 30is raised the rail sections 32 are lowered by the bell cranks 19 tolower the connecting rods C on rail sections 32 onto the weighingplatforms of the weighing scales 41 and 42 which respectively determinethe overweight of the crank pin and wrist pin ends of the connecting rodC at weigh station 3 and determine whether the milled connecting rod Cat the check weigh station 8 is within prescribed weight standardlimits.

The reject station 9 as best shown in FIGS. 2 and 5 comprises a rejectchute 45 and a rear rail section 46 which is swung to the phantom lineposition of FIG. 5 by the cylinder 47 and bell crank 48, the front railsection being formed with a beveled top face 49 to permit tilting of therejected'connecting rod C for sliding down the chute 45 when the railsection 46 swings down and is disengaged from the wrist pin end of theconnecting rod C. The cylinder 47 is actuated by the check weigh scale42 when the milled connecting rod C is outside the prescribed weightstandard limits. If the check weighed connecting rod C is of requiredstandard weight, the rear rail section 46 will be in the FIG. 5 solidline position whereby the check weighed connecting rod C will beadvanced successively to stations 9 and 10.

Referring now in detail to the weighing scale 41 at the weigh station 3and to the milling machines 56 at the milling station 5, each of thelatter as shown in FIGS. 3 and 8 comprises milling head slide 57 havinga spindle 58 which is driven by motor 59 and which has a milling cutter60 thereon adapted to be fed toward and away from the respective weightboss at the end of the connecting rod C clamped at milling station 5when the slide 57 is actuated along the ways 61 of the base 62 by theball feed screw 63,.the ball feed screw 63 being engaged with ball nut64 and being driven by the reversible motor 65.

The weighing scale 41 has duplicate control elements for the respectivemilling machines 56 and hence only one has been shown in FIG. from thecrank pin end of the connecting rod clamped at milling station 5. Inthis case the wellknown linear variable differential transformer 67(LVDT), such as the model N0. M1 manufactured by Comptrol, Inc.,Cleveland, Ohio, measures the amount of overweight of the crank pin endof the connecting rod C when the 8 for removal of metal I latter is atthe weigh station 3, the analog signal from said LVDT 67 being convertedby the well known analog to digital converter 68 to a digital amount ofover-- to digital converter 68, digital display unit 69, and storageunit 70 may be, for example, the model 148-65398 manufactured by MoogControls Division of Moog, Inc., East Aurora, N.Y.

The milling cutter 60 adaptive control herein illustrated senses thelocation of the end of the weight boss from which point the cutter 60 isadvanced in 0.001 inch increments until the length of stock correspondsto that stored in. the storage unit 70. Specifically the load of themilling cutter drive motor 59 is monitored by the load monitor 71, suchas model MEX-2137 manufactured by Machine Electrification, Inc.,Northboro, Mass, to sense the rate of increase in the load which occursbetween running at idle and when the cutter 60 contacts the weight boss.When the rate of increase is of specified adjustable value, operation ofthe conventional counter 72 is initiated in conjunction with a pulsegenerator 73 coupled to the feed motor 65 and with a standard comparatorcount down unit 74. Both the counter 7 2 and the pulse countdown unit 74may be, for example, the above model 148-65398 manufactured by MoogControls Division. The pulse generator 73 will be arranged to provide apulse for each 0.001 inch advance of the cutter 60 after suchpredetermined rate of increase of load. When the number of pulses equalsthe figure from the storage unit 70, the feed motor 65 is reversed.Although specific equipment has been set forth above to perform the wellknown functions of the L.V.D.T. 67, analog to digital converter 68,digital display unit 69, storage unit 70, load monitor 7 1, counter 72,and comparator 74, other similar devices may besubstituted for any oneor more thereof to provide a working machine in accordance with theinvention.

The rate of load increase in watts is preferably employed because it isnot affected by variation due to a cold or warm machine. However, it isto be understood that contact of the cutter 60 with the weight boss maybe sensed by increased current draw of the motor 59, by torsionaldeflection of the spindle 58, or by vibration pickup. The rate ofincrease of load should be adjusted so that a slight increase may occurwithout triggering the start of the measured weight boss removal, aswhen the cutter 60 engages forging flash or other irregularity on theweight boss. Tests have shown that a 0.5 gram of weight boss removalwill cause sufficient increase in cutter 60 load to uniformly sense thelocation from which the measured amount of weight boss removal starts.The digital display 69 is so arranged that the performance of themachine can be observed while it is cycling. The load monitor 71 mayalso be employed to control the feed motor 65 to reduce its speed fromrapid approach to milling feed when the cutter 60 contacts the weightboss thus to further reduce machine cycle time.

After both ends of a connecting rod C at station 5 have been milled, theconnecting rod C will be advanced successively through the two idlestations 6 and 7 and then to the check weigh station 8 which may have aweighing scale 41 essentially of the same construction as that at theweigh station 3 except that the LVDT 67 signal is transmitted to thereject station 9 in the event that the milled connecting rod C does notmeet the required weight specifications and when such reject signal istransmitted to the reject station 9, the reject cylinder 47 is actuatedto allow the non-standard weight connecting rod C to fall down thereject chute 45.1f the milled connecting rod C passes the requirementsof the check weigh station 8, it is allowed to pass the reject station 9and then be indexed to the unload station 10.

in an illustrative example of this invention, the stations 1 to 10 werespaced apart 10 inches and the machine cycle time was 0.034 minutes witha milling time of 0.041 minutes whereby the total floor to floor time ofthe connecting rods C was 0.075 minutes to provide a production (basedon maximum weight removal) of 800 connecting rods per hour or 900connecting rods per hour based on a mean length of weight boss removal.As apparent, the provision of the idle stations shortens the indexingstroke to 10 inches as aforesaid and of course, while the pilots 27 arein lowered position, and while the index bar 30 and rod engaging members35 and 36 are in raised position, the index bar 30 may be shifted totheleft to the FIG. 2 position during the time that the millingoperations are in progress whereby as soon as the milling operationshave been completed and as the milling cutters are being retracted, thebell crank actuating bar may be shifted to the right from the FIG. 2position to raise the pilots 27 and to lower the index bar 30 and rodengaging members and 36 followed by indexing movement of the index bar30 toward the right to advance the connecting rods C from station 1 to2, 2 to 3, etc. Of course, at the milling station 5, the clampingcylinder 38 is actuated to release the piloted clamps 39 from the milledconnecting rod C so that the milled connecting rod C may be'indexed fromstation 5 to the idle station 6.

In FIG. 9, the load monitor 80 is responsive to increased current drawof the spindle 58 drive motor 59 to sense when the cutter 60 engages theweight boss of the connecting rod C and the slide 57 is actuated by thehydraulic motor 81. As the cutter 60 advances toward the weight boss,the plunger 82 yields with respect to the plunger 33 of the LVDT 84 onthe base 85 by reason of the spring 86 being weaker than spring 87.However, when the cutter 60 engages the weight boss, the current draw ofmotor 59 increases to magnitude sufficient to actuate the clamp 89 andthereafter the plungers 82 and 83 move in unison and when the outputsignal from LVDT 84 matches that of the LVDT d7 of the weighing scale41, the hydraulic motor 81 is reversed.

to move the cutter 60 away from the milled weight boss.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A weight standardization machine for machining workpieces of variableoverweight to a predetermined workpieces from said weighing station tosaid work staweight standard comprising a weighing station whereat aweighing scale determines the magnitude of overweight of a workpiecethereon; a work station whereat a metal working machine having clampmeans for clamping a weighed workpiece thereat and cutter means movabletoward the clamped workpiece and into engagement therewith to removeexcess weight therefrom; sensing means to detect initial engagement ofsaid cutter means with the workpiece with the clamped workpiece; storagemeans to retain the overweight information from said weighing scale ofthe clamped workpiece to control the feed stroke of said cutter meanssubsequent to its initial engagement with the clamped workpiece toremove a prescribed weight of material to decrease its weight to suchstandard weight; and index means to index successive weighed tion.

2. The machine of claim 1 wherein said index means is further operativeto index successive overweight work pieces and successive machines workpieces, whereby the former are indexed to said weighing station and thelatter are indexed from said work station.

3. The machine of claim 1 wherein said machine has load and unloadstations respectively preceding and following said weighing and workstations, and idle stations between said load and weighing stations andsaid weighing and work stations to minimize the indexing stroke of saidindex means and thus shorten the cycle time of said machine.

4. The machine of claim 1 wherein said sensing means responds toincreased load on said cutter means.

5. The machine of claim 1 wherein said cutter means is a milling cuttermounted on a motor driven spindle of said milling machine; and whereinsaid milling machine has a motor driven feed slide which feeds saidspindle and milling cutter toward and into engagement with the clampedworkpiece; and wherein said sensing means responds to increased load onthe spindle drive motor.

' 6. The machine of claim 1 wherein said workpieces have weight bossesthereon of predetermined cross station area in a plane transverse to thefeed movement of said cutter means; and wherein a converter operativelyassociated with said weighing scale converts the overweight informationdetermined by said weighing scale to length of weight boss removal forretention in said storage means to control the feed stroke of saidcutter means subsequent to initial engagement thereof with the clampedworkpiece whereby a prescribed weight of weight boss will be removed bysaid cutter means to decrease the weight of the clamped workpiece tosuch standard weight.

7. The machine of claim 1 wherein said machine has a check weighingstation and a reject station following said workstation; said checkweighingstation having another weighing scale thereat to determinewhether the successive machined workpieces thereon are within prescribedlimits of such standard weight; and said reject station being operativein conjunction with said another weighing scale to divert substandardworkpieces from the machine.

1. A weight standardization machine for machining workpieces of variableoverweight to a predetermined weight standard comprising a weighingstation whereat a weighing scale determines the magnitude of overweightof a workpiece thereon; a work station whereat a metal working machinehaving clamp means for clamping a weighed workpiece thereat and cuttermeans movable toward the clamped workpiece and into engagement therewithto remove excess weight therefrom; sensing means to detect initialengagement of said cutter means with the workpiece with the clampedworkpiece; storage means to retain the overweight information from saidweighing scale of the clamped workpiece to control the feed stroke ofsaid cutter means subsequent to its initial engagement with the clampedworkpiece to remove a prescribed weight of material to decrease itsweight to such standard weight; and index means to index successiveweighed workpieces from said weighing station to said work station. 2.The machine of claim 1 wherein said index means is further operative toindex successive overweight work pieces and successive machines workpieces, whereby the former are indexed to said weighing station and thelatter are indexed from said work station.
 3. The machine of claim 1wherein said machine has load and unload stations respectively precedingand following said weighing and work stations, and idle stations betweensaid load and weighing stations and said weighing and work stations tominimize the indexing stroke of said index means and thus shorten thecycle time of said machine.
 4. The machine of claim 1 wherein saidsensing meaNs responds to increased load on said cutter means.
 5. Themachine of claim 1 wherein said cutter means is a milling cutter mountedon a motor driven spindle of said milling machine; and wherein saidmilling machine has a motor driven feed slide which feeds said spindleand milling cutter toward and into engagement with the clampedworkpiece; and wherein said sensing means responds to increased load onthe spindle drive motor.
 6. The machine of claim 1 wherein saidworkpieces have weight bosses thereon of predetermined cross stationarea in a plane transverse to the feed movement of said cutter means;and wherein a converter operatively associated with said weighing scaleconverts the overweight information determined by said weighing scale tolength of weight boss removal for retention in said storage means tocontrol the feed stroke of said cutter means subsequent to initialengagement thereof with the clamped workpiece whereby a prescribedweight of weight boss will be removed by said cutter means to decreasethe weight of the clamped workpiece to such standard weight.
 7. Themachine of claim 1 wherein said machine has a check weighing station anda reject station following said work station; said check weighingstation having another weighing scale thereat to determine whether thesuccessive machined workpieces thereon are within prescribed limits ofsuch standard weight; and said reject station being operative inconjunction with said another weighing scale to divert substandardworkpieces from the machine.